What is the mechanism for proton decay in the Standard Model?

In summary, the SM does not have baryon and lepton number as exact symmetries, allowing for the possibility of proton decay with smaller probabilities compared to GUT's. This decay mechanism is non-perturbative and involves topological effects in the SDM. While the contribution is very small, it can still be detected. Cosmologists were excited about this in the early 90s for leptogenesis models. T'Hooft's original paper from 1976 is not available online, but there are experimental papers and review articles discussing this topic.
  • #1
zefram_c
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I recently saw posts indicating that the SM does not have baryon and lepton number as exact symmetries, and in fact allows protons to decay, but with much smaller probabilities than GUT's. What is the mechanism by which such decays can occur (is it non-perturbative?), and what order of magnitude are the amplitudes for such processes?
 
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Yea it is nonperturbative, actually a topological effect in the sdm.

Its a vanishingly small contribution, but still in principle detectable.. Cosmologists were very excited about this back in the early 90s for leptogenesis models.

I can't find T'Hooft's original 1976 paper online, but here is an experimental papers on the matter, which should include some discussion suitable for a novice.

http://arxiv.org/PS_cache/hep-ph/pdf/0307/0307034.pdf [Broken]

as well as a review article (I actually found a few errors in this one, but whatever its ok)

http://arxiv.org/PS_cache/hep-ph/pdf/0209/0209227.pdf [Broken]
 
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1. What is proton decay within the Standard Model (SM)?

Proton decay within the SM is a theoretical phenomenon that suggests that protons, one of the building blocks of matter, may eventually decay into smaller particles. This idea is based on the fact that the SM predicts that all particles have a finite lifetime, including protons.

2. Is proton decay within the SM possible?

While the SM does predict that protons can decay, there is currently no experimental evidence to support this theory. Scientists are still actively researching and conducting experiments to try and detect any proton decay events.

3. How does proton decay within the SM occur?

In the SM, protons can decay through a process known as baryon number violation, which involves the conversion of a proton into a lighter particle, such as a positron or a meson. This process is also known as lepton number violation, as the number of leptons (electron-like particles) also changes.

4. Why is proton decay within the SM important?

If experimental evidence of proton decay is found, it would provide further support for the SM, which is currently the most widely accepted theory for understanding the fundamental particles and forces of the universe. It could also help explain the dominance of matter over antimatter in the universe.

5. What are the current limitations in studying proton decay within the SM?

One of the main limitations is that proton decay is a rare event, which makes it difficult to detect. Additionally, the predicted timescale for proton decay within the SM is extremely long, on the order of 10^32 years, making it even more challenging to observe. This means that scientists must continue to develop new and more sensitive detection methods in order to study proton decay within the SM.

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